Yes, Nivi came into the marriage with honesty with Viren. He kept a huge secret and then was the one who was her stalker. How is this even comparable to why she came into the marriage?
But when she blamed Viren, did he ever apologize to her? Has he ever said he is sorry throughout this whole thing? He had the chance to say he was sorry and tell her that he loves her and ask her not to go.
He gives the reason that she should not leave the family but says nothing of their relationship.
If I was Nivi, I would have left too. I would never stay with a man who I thought was only using me and didn't love me. If Viren at that moment had cried and said he loves her and asked her to stay, she would have. But he didn't so she left ...